1. Field of the Invention
The present invention relates to battery caps for insertion into fill ports of a lead-acid storage battery, particularly deep cycle, high charge and high discharge batteries of the type utilized on golf carts and other battery powered vehicles.
2. Description of the Prior Art
A typical lead-acid battery consists of a plurality of cells filled with aqueous sulfuric acid electrolyte. The cells employ negative plates using lead as the electroactive material and positive plates in which lead oxide is the electroactive material. Sets of an equal number of positive and negative plates in the electrolyte are referred to as cells. Each lead-acid cell produces two volts per cell. The assembly of several cells in a series circuit to produce a higher voltage is called a battery.
Each cell in a battery has a fill opening which requires a battery cap. The purpose of the fill opening is to provide an opening for electrolyte filling and water replacement. The fill opening also provides a path to vent gas that is produced during charging and discharging of the battery.
The purpose of the battery cap is to prevent the electrolyte from spilling or spewing from the battery cells. The sulfuric acid battery electrolyte is highly caustic and can cause injury to persons upon contact, eat holes in clothing and other fabric materials, and rapidly corrode metal if it is ejected from the battery. Therefore, it is highly desirable to prevent electrolyte from escaping the battery case. During charging a battery generates bubbles within the acid that can and do spew electrolyte from the battery unless precautions are taken. Conventional prior art battery caps are therefore equipped with splash guards, baffles and other devices designed to recover and return to the battery cells electrolyte spewed from the battery.
Lead-acid cell batteries have intrinsic hazards. It is well known that lead-acid storage batteries utilized on motor vehicles emit potentially explosive gases during charging and discharging. During the normal course of charging and discharging a battery, a potentially explosive mixture of oxygen and hydrogen is liberated. A conventional battery cap is not a solid structure, but is typically hollow and includes one or more passageways to vent the mixture of oxygen and hydrogen from the battery compartment to the atmosphere at a slow rate. This process is referred to as off-gassing.
An inherent danger that accompanies the off gassing process is the possibility that a spark, flash or flame might enter the battery cell through the vent passageway of a battery cap. If this occurs the volatile, explosive gases are ignited within the battery, whereupon the battery will explode. If this happens acid and battery fragments are thrown through the air. When this occurs damage to the battery compartment is very likely, and the risk of personal injury is quite great.
Because of the risk of personal injury and property damage that may occur, original equipment manufacturers (OEM""s) and battery distributors have insisted in recent years that battery caps utilized on batteries with which they deal must be APF (flame retardant approved). This is achieved by utilizing a microporous disc as a flame barrier in each battery cap. This microporous disc acts as a spark or flame arrester.
One problem created by porous disc spark arresters is the xe2x80x9cloadingxe2x80x9d or destruction of the porosity of the microporous filter from suspended particulate contamination carried by the gas bubbles during off gassing. Such contaminants do not pass through the microporous filter but are instead loaded into the open pores of the porous disc. As a result of this process the porosity of the filter disc is reduced from its design specifications. As this occurs internal battery gas pressure rises. As pressure increases above and beyond atmospheric pressure, battery acid is spewed through a conventional battery cap and into a battery compartment. This results in a loss of electrolyte which, when it escapes the battery, is likely to cause injury or damage.
Also, the buildup of gas pressure within a battery alters the xe2x80x9cbattery envelopexe2x80x9d. That is, gas pressure buildup within a battery alters the outside dimensions of the battery. The battery bulges and can damage the battery compartment. Also, unless pressure is relieved the battery can crack and leak electrolyte.
In the past battery caps have been designed to attempt to solve these problems. In some cases the porous disc is protected by splash guards. Examples of battery caps constructed in this way are described, for example, in U.S. Pat. Nos. 5,422,199; 5,209,992; 4,400,450; and 5,132,175. Also, some battery caps have been designed with labyrinth paths. Examples of these types of battery caps are found in U.S. Pat. Nos. 5,132,175; 5,209,992; and 5,422,199. In other battery caps special types of chambers have been constructed. Examples of these appear in U.S. Pat. Nos. 4,400,450; 5,132,175 and 5,422,199.
Some conventional battery caps perform satisfactorily when utilized on relatively shallow cycle batteries of the type employed for ignition in a gasoline or diesel fuel powered vehicle. However, until the present invention battery caps employing microporous disc spark or flame arresters have not been feasible for use with the high charge and high discharge batteries required as the sole power source for vehicles such as golf carts, warehouse forklifts and other such vehicles. Some of the deep cycle batteries suitable for such vehicles are sold with the trade designations 250""s, L16""s, J185""s, and Scrubbers.
The introduction of the widespread requirement for spark and flame arresters has created a new set of problems in lead-acid electrical storage batteries. One of these problems is the interruption of the natural equilibrium of the internal gas pressure within a battery cell and the outside atmosphere. This imbalance in equilibrium is made progressively worse by the deterioration of the porous disc spark or flame arrester. This deterioration results from the agglomeration of particulate contaminants in the porous disc that are carried in the aqueous electrolyte solution.
During the usual charging and discharging cycle of a battery the negative lead plates and positive lead oxide plates of the battery gradually erode. Particles from the heavy-metal plates are carried into the aqueous sulfuric acid electrolyte as dissolved, particulate matter. These particles eventually precipitate to the bottom of the battery. This byproduct is called xe2x80x9cmudxe2x80x9d in the battery industry.
During agitation and jostling of the battery that occurs as a battery powered vehicle travels, the particles of xe2x80x9cmudxe2x80x9d are carried into suspension in the electrolyte. These particles are ultimately transported to the microporous flame arrester by gas bubbles created in the electrolyte during charging and discharging and by spewing electrolyte.
One important object of the present invention is to provide a battery cap which does incorporate a spark or flame arrester for used in a deep charge, lead-acid electrical storage battery of the type used to power golf carts, forklifts and similar vehicles.
A related object of the invention is to provide a battery cap that solves the problem of pressure buildup and envelope expansion in deep cycle lead-acid electrical storage batteries.
In one broad aspect the present invention may be considered to be a battery cap for insertion into a fill port of a cell of a lead-acid electrical storage battery comprising a hollow, tubular body, a diverter located within the tubular body, a flame arrester located within the tubular body above the diverter, and a top end closure.
The tubular body is a hollow, barrel shaped body having upper and lower ends. It is formed with an upright, annular wall having an exterior configured to engage a battery fill port. The wall has a first snap fit engaging element on its inner surface at the upper end of the body. The upper end of the body defines a circular mouth opening. An annular, transverse floor extends radially inwardly from the wall at the lower end of the body. The floor includes a central, annular downwardly bulging portion perforated by a central fluid passage opening therein. The wall also defines a radially inwardly projecting flame arrester seat located between the upper and lower ends of the body. The wall further defines a plurality of laterally spaced gas escape ports beneath the mouth opening,
The diverter is located within said body and is formed with a transverse plate having fluid passageways at its periphery. A plurality of upright plate supports are formed as segments of an upright hollow cylinder, and extend downwardly from the transverse plate. The plate supports define radial fluid passage gaps therebetween. The plate supports rest upon the floor of the body and straddle the central, fluid passage opening and hold the transverse plate directly above the downwardly bulging portion of the floor at a location spaced above the floor.
The porous flame arrester is disposed upon the flame arrester seat and extends across the interior of the tubular body and resides in contact with the interior surface of the upright wall throughout its circumference.
The top end closure disc has a second snap fit engaging element at its periphery. The first snap fit engaging element at the top of the wall and the second snap fit engaging element on the top end closure disc are engaged with each other at the top end of the body to hold the top end closure disc engaged with the wall to block the circular mouth opening of the body.
Preferably, the interior of the wall is formed with a radially inwardly projecting diverter engaging ring. The diverter engaging ring is located between the floor and the flame arrester seat. The area between the floor and the flame arrester seat thereby forms a diverter cavity.
The diverter is formed of plastic and is entrapped in the diverter cavity by the diverter engaging ring. The diverter plate is preferably formed in a disc shaped configuration with a pair of diametrically opposed notches in its periphery. The spaces between the structure of the plate at the notches and the interior of the wall form the peripheral fluid passageways.
The plastic of which the diverter is formed is stiff, but is sufficiently resilient so that the edges of the diverter plate will flex so that they clear the diverter engaging ring as the diverter is pressed downwardly toward the floor of the tubular body. As the configuration and are entrapped beneath the diverter engaging ring. The diameter of the diverter plate is just slightly greater than the inner diameter of the hollow area across the tubular body encompassed within the diverter engaging ring.
Preferably also the top end closure disc has a concealed inner surface facing the flame arrester and a finger projecting from the concealed inner surface toward the flame arrester. This longitudinally projecting finger resides in contact with the flame arrester when the snap fit engaging elements on the upper end of the wall and the top end closure are engaged with each other. The finger thereby serves as a means for preventing the top end closure disc from being forced too far down into the tubular body. The finger also serves to hold the porous flame arrester in position against the flame arrester seat. The flame arrester seat may be formed as an upwardly facing, annular bearing ledge by a radially inwardly extending ring shaped projection from the interior of the wall of the tubular body.
A pair of gas escape ports are located side-by-side at the same longitudinal distance along the axis of longitudinal alignment of the tubular body from the top end closure disc. The gas escape ports are located in laterally spaced separation from each other in the wall between the end closure disc and the flame arrester. The gas escape ports serve to allow gases to escape from the battery cells, thus avoiding gas pressure buildup within the battery cells.
In another broad aspect the invention may be considered to be a battery cap for a fill port of a cell of a lead-acid electrical storage battery. The battery cap of the invention is comprised of a hollow, tubular body formed with top and bottom ends and an upright tubular wall. The wall has an exterior and an interior surrounding a central axis of longitudinal alignment. The exterior of the wall is configured to engage the fill port. The upper extremity of the interior of the wall forms an upper mouth opening at the top end of the tubular body. A lower end closure floor is formed at the bottom end of the tubular body at the lower extremity of the wall. A pair of laterally spaced gas escape ports are defined through the wall below the upper mouth opening.
The interior of the wall forms a flame arrester seat located between the floor and the pair of gas escape ports. The floor has a central, annular portion centered on the axis of longitudinal alignment. This central, annular portion has a convex downwardly bulging exterior end face. A central, circular fluid passage opening is defined through the central annular portion of the floor.
A diverter is located within the tubular body and has a plate oriented perpendicular to the axis of longitudinal alignment. The diverter plate has peripheral fluid passageways at its periphery. Upright supports project downwardly from the plate. The supports are shaped as arcuately curved segments of an upright cylinder centered on the axis of longitudinal alignment. The upright supports rest upon the floor at the central annular portion thereof to hold the plate in spaced separation from the floor directly above the central annular portion of the floor. The supports define a pair of diametrically opposed, radial fluid passage gaps therebetween,
A transverse, porous flame arrester is located above the diverter and below the pair of gas escape ports. The flame arrester resides in contact with the wall throughout the interior thereof. A body end closure blocks the upper mouth opening and is secured to the wall at the top end of the body in interlocking engagement therewith.
The invention may be described with greater clarity and particularity by reference to the accompanying drawings.